Laminates, electronic devices, solar cells, multi-junction solar cells, solar cell modules, and photovoltaic power generation systems

Abstract

We provide laminates, electronic devices, solar cells, multi-junction solar cells, solar cell modules, and photovoltaic power generation systems with superior properties. [Solution] The laminate of the embodiment comprises a substrate, a transparent electrode provided on the substrate, and an insulating film provided on the transparent electrode that covers 50% to 100% of the surface of the transparent electrode opposite to the substrate side, and is thinner than the substrate.

Description

[Technical Field]

[0001] The present invention relates to a laminate, electronic equipment, solar cell, multi-junction solar cell, solar cell module, and photovoltaic power generation system. [Background technology]

[0002] One new type of solar cell uses cuprous oxide (Cu2O) as its light-absorbing layer. Cu2O is a wide-bandgap semiconductor. Because Cu2O is a safe and inexpensive material composed of copper and oxygen, which are abundant on Earth, it is expected to enable the creation of highly efficient and low-cost solar cells. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Bart Vermang et. al., Development of rear surface passivated Cu(In,Ga)Se2 thin film solar cells with nano-sized local rear point contacts, Solar Energy Materials & Solar Cells 117 (2013) 505-511. [Overview of the project] [Problems that the invention aims to solve]

[0004] The problem that this invention aims to solve is to provide laminates, electronic devices, solar cells, multi-junction solar cells, solar cell modules, and photovoltaic power generation systems with excellent properties. [Means for solving the problem]

[0005] The laminate of the embodiment comprises a substrate, a transparent electrode provided on the substrate, and an insulating film provided on the transparent electrode that covers 50% to 100% of the surface of the transparent electrode opposite to the substrate side, and is thinner than the substrate. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a schematic cross-sectional view of the laminate according to the embodiment. [Figure 2] Figure 2 illustrates the analysis spots of the solar cell according to the embodiment. [Figure 3] Figure 3 is a schematic cross-sectional view of the electronic device according to the embodiment. [Figure 4] Figure 4 is a schematic cross-sectional view of the electronic device according to the embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view of the electronic device according to the embodiment. [Figure 6] Figure 6 is a schematic cross-sectional view of a solar cell according to an embodiment. [Figure 7] Figure 7 is a cross-sectional view of a multi-junction solar cell according to an embodiment. [Figure 8] Figure 8 is a perspective view of a solar cell module according to an embodiment. [Figure 9] Figure 9 is a cross-sectional view of a solar cell module according to an embodiment. [Figure 10] Figure 10 is a diagram showing the configuration of a solar power generation system according to an embodiment. [Figure 11] Figure 11 is a schematic diagram of the vehicle according to the embodiment. [Figure 12] Figure 12 is a schematic diagram of the drone according to the embodiment. [Figure 13] Figure 13 is a table relating to the examples. [Figure 14] Figure 14 is a cross-sectional image of the solar cell in the example. [Figure 15] Figure 15 is a cross-sectional image of the solar cell in the example. [Figure 16] Figure 16 is a table relating to the examples. [Figure 17] Figure 17 is a table relating to the examples. [Modes for carrying out the invention]

[0007] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. Unless otherwise specified, physical property values are shown at 25°C and 1 atm (atmosphere). Also, the average represents the arithmetic mean value. Each concentration is the average concentration of the target region or layer. In each layer, the presence of a specific element means, for example, an element whose presence is confirmed by SIMS (Secondary Ion Mass Spectrometry), and the absence of a specific element means, for example, an element whose presence cannot be confirmed by SIMS.

[0008] In the specification, " / " represents the division symbol. However, the " / " in "or / and" means "or". In the specification, "·" and "*" represent the multiplication symbol. The "." in the numerical values of the specification represents the decimal point.

[0009] (First Embodiment) The first embodiment relates to a laminate. FIG. 1 shows a schematic cross-sectional view of the laminate 10 of the first embodiment. The laminate 10 shown in FIG. 1 has a substrate 1, a transparent electrode 2, and an insulating film 3, and has an insulating film that covers 50% or more and 100% or less of the surface of the transparent electrode on the side opposite to the substrate side and is thinner than the substrate.

[0010] The substrate 1 is a transparent substrate. For the substrate 1, organic substrates such as acrylic, polyimide, polycarbonate, polyethylene terephthalate (PET), polypropylene (PP), fluorine-based resins (polytetrafluoroethylene (PTFE), perfluoroethylene propene copolymer (FEP), ethylene tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), perfluoroalkoxyalkane (PFA), etc.), polyarylate, polysulfone, polyethersulfone, and polyetherimide, and inorganic substrates such as soda lime glass, whiteboard glass, chemically strengthened glass, and quartz that transmit light can be used. The substrate 1 may be a laminate of the above-mentioned substrates.

[0011] The transparent electrode 2 is provided on the substrate 1 and is positioned between the substrate 1 and the insulating film 3. The transparent electrode 2 is a planar conductive film. The transparent electrode 2 is a light-transmitting conductive layer. Preferably, the transparent electrode 2 contains one or more oxide transparent conductive films. The oxide transparent conductive film can be a semiconductor conductive film such as indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), boron-doped zinc oxide (BZO), gallium-doped zinc oxide (GZO), doped tin oxide, titanium-doped indium oxide (ITiO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), or hydrogen-doped indium oxide (IOH), and is not particularly limited. The oxide transparent conductive film may also be a multilayer film having multiple layers. The dopant for the tin oxide film is not particularly limited as long as it is one or more elements selected from the group consisting of In, Si, Ge, Ti, Cu, Sb, Nb, Ta, W, Mo, F, and Cl. The transparent electrode 2 preferably contains a tin oxide film doped with one or more elements selected from the group consisting of In, Si, Ge, Ti, Cu, Sb, Nb, Ta, W, Mo, F, and Cl. In the doped tin oxide film, it is preferable that one or more elements selected from the group consisting of In, Si, Ge, Ti, Cu, Sb, Nb, Ta, W, Mo, F, and Cl are present in an amount of 10 atomic percent or less relative to the tin contained in the tin oxide film. As the transparent electrode 2, a laminated film can be used, which is a laminate of an oxide transparent conductive film and a metal film. The metal film preferably has a thickness of 1 [nm] to 2 [μm], and the metal (including alloys) contained in the metal film is not particularly limited, such as Mo, Au, Cu, Ag, Al, Ta, and W.Furthermore, the transparent electrode 2 preferably includes dot-shaped, line-shaped, or mesh-shaped electrodes (one or more selected from the group consisting of metals, alloys, graphene, conductive nitrides, and conductive oxides) between the oxide transparent conductive film and the substrate 1. The dot-shaped, line-shaped, or mesh-shaped metal preferably has an aperture ratio of 50% or more relative to the oxide transparent conductive film. The dot-shaped, line-shaped, or mesh-shaped metal is not particularly limited to Mo, Au, Cu, Ag, Al, Ta, or W. When a metal film is used for the transparent electrode 2, the film thickness is preferably about 5 nm or less from the viewpoint of transparency. When a line-shaped or mesh-shaped metal film is used, transparency is ensured at the aperture, so this does not apply to the film thickness of the metal film.

[0012] Specific examples of transparent electrode 2 include a transparent electrode composed of an ITO film, and a transparent electrode in which the doped tin oxide film is located on the insulating film side, in a laminated film of an ITO film and a doped tin oxide film.

[0013] The insulating film 3 is a film containing an insulating material provided on the transparent electrode 2. The side of the laminate 10 opposite to the substrate 1 side (the side on which the insulating film 3 is provided) is electrically conductive at least partially. The thickness direction of the insulating film 3 is the stacking direction of the laminate 10.

[0014] The thickness of the transparent electrode 2 is preferably 50 nm to 500 nm, more preferably 50 nm to 300 nm, and even more preferably 75 nm to 200 nm. By using the insulating film 3, even if the thickness of the transparent electrode 2 is very thin, such as 75 nm to 200 nm, the sheet resistance of the device in which the laminate 10 is assembled becomes low.

[0015] The insulating film 3 is in direct contact with the transparent electrode 2. The insulating film 3 is in direct contact with the surface of the transparent electrode 2 opposite to the substrate 1 side (the surface of the transparent electrode 2 facing the insulating film 3 side). Preferably, the transparent electrode 2 contains an oxide transparent conductive film on the side closest to the insulating film 3, and the insulating film 3 is in direct contact with the surface of the oxide transparent conductive film located closest to the insulating film 3 on the transparent electrode 2 opposite to the substrate 1 side (the surface of the oxide transparent conductive film located closest to the insulating film 3 on the transparent electrode 2 facing the insulating film 3 side).

[0016] It is preferable that the surface of the insulating film 3 facing the transparent electrode side is in direct contact with the transparent electrode 2. It is preferable that the entire surface of the insulating film 3 facing the transparent electrode 2 side is in direct contact with the transparent electrode 2.

[0017] The insulating film 3 preferably covers 50% to 100% of the surface of the transparent electrode 2 opposite to the substrate 1 side, more preferably 95% to 100%, and even more preferably 99% to 100%.

[0018] The insulating film 3 can cover the entire surface of the transparent electrode 2 opposite to the substrate 1 side.

[0019] The insulating film 3 preferably contains one or more insulating materials selected from the group consisting of SiO2, Al2O3, SiN, SiON, and MgO. The insulating film 3 is so-called glass or ceramics. The insulating film 3 is preferably composed of an inorganic material. The insulating film 3 is preferably an amorphous film.

[0020] The insulating film 3 contains one or more elements selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, SiN, SiON, and MgO, and it is preferable that the total amount of one or more elements selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, SiN, SiON, and MgO contained in the insulating film 3 is 70 [wt%] or more and 100 [wt%] or less of the insulating film 3. In addition to the above oxides, the insulating film 3 may also contain oxides such as Li2O, K2O, CaO, BaO, SrO, ZnO, ZrO2, PbO, TiO2, HfO2, and Sb2O3.

[0021] If the total amount of one or more elements selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, SiN, SiON, and MgO contained in the insulating film 3 is 95 [wt%] or more and 100 [wt%] or less, it is preferable that the total amount of one or more elements selected from the group consisting of SiO2, Al2O3, SiN, SiON, and MgO contained in the insulating film 3 is 50 [wt%] or more and 100 [wt%] or less of the insulating film 3, and more preferably 60 [wt%] or more and 100 [wt%] or less.

[0022] The insulating film 3 contains one or more elements selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, and MgO, and the total amount of one or more elements selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, and MgO contained in the insulating film 3 is preferably 70 [wt%] or more and 100 [wt%] or less of the insulating film 3, and more preferably 50 [wt%] or more and 100 [wt%] or less of the insulating film 3, and more preferably 60 [wt%] or more and 100 [wt%] or less of the insulating film 3.

[0023] Preferably, the total amount of one or more elements selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, and MgO in the insulating film 3 is 70 [wt%] or more and 100 [wt%] or less of the insulating film 3, and preferably the total amount of SiO2 and Al2O3 in the insulating film 3 is 50 [wt%] or more and 100 [wt%] or less of the insulating film 3, and more preferably 60 [wt%] or more and 100 [wt%] or less.

[0024] The total amount of one or more elements selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, and MgO in the insulating film 3 is preferably 70 [wt%] or more and 100 [wt%] or less of the insulating film 3, and it is preferable that the amount of SiO2 in the insulating film 3 is 50 [wt%] or more and 100 [wt%] or less of the insulating film 3, and more preferably 60 [wt%] or more and 100 [wt%] or less.

[0025] Preferably, the total amount of one or more compounds selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, and MgO in the insulating film 3 is 70 [wt%] or more and 100 [wt%] or less of the insulating film 3, the most abundant compound in the insulating film 3 is SiO2, and the total amount of SiO2 and Al2O3 in the insulating film 3 is 50 [wt%] or more and 100 [wt%] or less of the insulating film 3, and more preferably 60 [wt%] or more and 100 [wt%] or less.

[0026] The total amount of one or more compounds selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, and MgO in the insulating film 3 is preferably 70 [wt%] or more and 100 [wt%] or less of the insulating film 3, the most abundant compound in the insulating film 3 is SiO2, and it is preferable that the amount of SiO2 in the insulating film 3 is 50 [wt%] or more and 100 [wt%] or less of the insulating film 3, and more preferably 60 [wt%] or more and 100 [wt%] or less.

[0027] The insulating film 3 is preferably mainly composed of SiO2 or Al2O3 (the compound with the highest composition ratio [wt%] among the compounds contained in the insulating film 3). Preferable materials include soda-lime glass (e.g., mainly composed of SiO2 and containing Na2O and CaO), SiO2, Al2O3, white glass (e.g., mainly composed of SiO2 and containing Na2O, K2O, CaO, BaO, ZnO, TiO2 and Sb2O3), aluminosilicate glass (e.g., mainly composed of SiO2 and containing CaO and B2O3), or borosilicate glass (e.g., mainly composed of SiO2 and containing Na2O, Al2O3 and B2O3), with soda-lime glass and SiO2 being more preferred.

[0028] The composition of the insulating film 3 can be determined, for example, by analyzing analysis spots (A1-A9) that are distributed as evenly as possible and without gaps, as shown in the diagram illustrating the analysis spots in Figure 2, using TEM-EDX (Transmission Electron Microscopy-Energy Dispersive X-ray Spectroscopy). Figure 2 is a schematic diagram of the laminate 10 viewed from the insulating film 3 side. When analyzing the composition of the laminate 10, D1 is the length in the width direction (long side direction) of the laminate 10, and D2 is the length in the depth direction (short side direction) of the laminate 10. The thickness of the insulating film 3 can be determined by observing a 100 [nm] × 100 [nm] region including the center of each analysis spot by magnification 2,000,000 times with TEM. Alternatively, the composition can be determined from the elemental mapping obtained by EDX. Furthermore, by analyzing the center of each analysis spot in the thickness direction of the laminate 10 with XPS, the chemical bonding state can be evaluated, and the compounds of elements contained in the insulating film 3 can be identified.

[0029] The insulating film 3 is thinner than the substrate 1. The average thickness of the insulating film 3 is 10 times the thickness of the substrate 1. -8 more than 10 times -3 It is preferable that it be less than or equal to 5 x 10 -7 More than 5x10 -3 The following is more preferable: 5 × 10 -7 More than 5x10 -4 The following is even more preferable: The thickness of the insulating film 3 is preferably 1 nm or more and 50 nm or less, more preferably 1 nm or more and 30 nm or less, and even more preferably 3 nm or more and 20 nm or less.

[0030] The thickness of the insulating film 3 is determined by observing the cross-section in the thickness direction of the laminate 10. The area S[nm] of the insulating film 3 present in a length 10[nm] width of the cross-sectional image is determined. 2 ] calculate the area S[nm 2The average thickness of the insulating film 3, which is the value obtained by dividing ] by 10, is taken as the thickness of the insulating film 3, which is 10 nm wide. The width of one analysis spot is set to 100 nm, and the thickness of 10 locations can be determined for each analysis spot. Similarly, the thickness can be determined for 9 analysis spots, so the thickness of the insulating film 3 at 90 locations can be determined for one laminate 10. For example, if the thickness of the insulating film 3 is between 1 nm and 50 nm, it means that the thickness of the insulating film 3 at 90 locations is within the range of 1 nm and 50 nm. The average value of the thickness of the insulating film 3 is the average value of the thickness at 90 locations. The maximum thickness of the insulating film 3 is the maximum value of the thickness at 90 locations. Parts where the thickness of the insulating film 3 is less than 0.1 nm are considered to be parts where the insulating film 3 is not provided on the transparent electrode 2. In order to adopt the above analysis method, the lower limit of the thickness of the insulating film 3 is 0.1 nm.

[0031] The average thickness of the insulating film 3 is preferably 1 nm or more and 30 nm or less, preferably 1.5 nm or more, more preferably 3 nm or more and 25 nm or less, and even more preferably 5 nm or more and 20 nm or less.

[0032] The average thickness of the insulating film 3 is preferably 1 nm or more and 10 nm or less, preferably 1.5 nm or more and 10 nm or less, more preferably 3 nm or more and 25 nm or less, and even more preferably 5 nm or more and 20 nm or less.

[0033] The minimum thickness of the insulating film 3 is preferably 0.1 times or more and 1 time less than or equal to the average thickness of the insulating film 3, more preferably 0.3 times or more and 1 time less than or equal to the average thickness of the insulating film 3, and even more preferably 0.5 times or more and 1 time less than or equal to the average thickness of the insulating film 3.

[0034] The maximum thickness of the insulating film 3 is preferably 1 to 10 times the average thickness of the insulating film 3, more preferably 1 to 5 times, and even more preferably 1 to 3 times.

[0035] The thickness distribution of the insulating film 3 preferably has a maximum peak within the range of 5 nm to 15 nm. If other peaks exist within the range of 5 nm to 15 nm, the height of the other peaks is preferably 50% or less of the height of the maximum peak. The full width at half maximum of the thickness distribution of the insulating film 3 is preferably 1 nm to 10 nm.

[0036] The side of the insulating film 3 of the laminate 10 that is opposite to the side facing the transparent electrode 2 is exposed.

[0037] For example, a transparent electrode 2 can be formed on a substrate 1 by sputtering, and an insulating film 3 can be deposited on the transparent electrode 2 by sputtering or ALD (Atomic Layer Deposition) to obtain a laminate 10.

[0038] Preferably, the light transmittance of the laminate 10 using the transparent electrode 2 in the wavelength range of 700 nm to 1000 nm is 65% or more, and the light transmittance of the light in the wavelength range of 800 nm to 1000 nm is 70% or more.

[0039] The laminate 10 equipped with the insulating film 3 is transparent, and after a semiconductor layer or the like is formed on the insulating film 3, the insulating film 3 side can electrically contact the transparent electrode 2, and can be used in virtually the same way as a material without the insulating film 3. When a semiconductor layer or the like is formed on the laminate 10, the insulating film 3 is thought to function as a barrier layer that prevents elements from diffusing from the semiconductor layer or the like to the transparent electrode 2, and is thought to contribute to preventing the transparent electrode 2 from becoming highly resistive.

[0040] (Second Embodiment) The second embodiment relates to an electronic device. The electronic device of the second embodiment has a laminate 10 and a liquid crystal layer, an emissive layer, or a semiconductor layer provided on an insulating film 3 of the laminate 10. By forming a semiconductor layer or the like on the insulating film 3, the thickness of the insulating film 3 in the second embodiment changes to a different thickness from that of the insulating film 3 in the first embodiment. The insulating film 3 in the first embodiment does not have the thin and thick portions of the second embodiment, but the insulating film 3 in the second embodiment does have the thin and thick portions. The thickness of the insulating film 3 in the first embodiment is different from the thickness of the insulating film 3 in the second embodiment.

[0041] Figure 3 shows a schematic cross-sectional view of an electronic device 11 having a liquid crystal layer 20. The electronic device 11 has a laminate 10, a liquid crystal layer 20, and electrodes 21. The electronic device 11 is, for example, a display. The liquid crystal layer 20 is located between the insulating film 3 of the laminate 10 and the electrodes 21. The liquid crystal layer 20 has, for example, liquid crystal sandwiched between alignment films. The liquid crystal layer 20 is electrically connected to the transparent electrodes 2 of the laminate 10. The laminate 10 is suitable as a substrate equipped with electrodes for a display.

[0042] Figure 4 shows a schematic cross-sectional view of an electronic device 12 having an emissive layer 22. The electronic device 12 has a laminate 10, an emissive layer 22, and electrodes 21. The electronic device 12 is, for example, a display. The emissive layer 22 is located between the insulating film 3 of the laminate 10 and the electrodes. The emissive layer 22 has, for example, a polymer emissive layer and a hole injection layer. The polymer emissive layer or hole injection layer of the emissive layer 22 is electrically connected to the transparent electrodes 2 of the laminate 10. The laminate 10 is suitable as a substrate equipped with electrodes for a display.

[0043] Figure 5 shows a schematic cross-sectional view of an electronic device 13 having a semiconductor layer 23. The electronic device 13 comprises a laminate 10 and a semiconductor layer 23. The electronic device 13 is used, for example, in a semiconductor device including a solar cell. The semiconductor layer 23 includes, for example, a compound semiconductor. The semiconductor layer 23 is electrically connected to the transparent electrode 2 of the laminate 10. The laminate 10 is suitable as a substrate equipped with electrodes for a semiconductor device.

[0044] The insulating film 3 of the second embodiment includes at least a portion of a thin portion that allows current to flow in the thickness direction of the laminated structure 10. The liquid crystal layer 20 of the electronic device 11 is electrically connected to the transparent electrode 2. The light-emitting layer 22 of the electronic device 12 is electrically connected to the transparent electrode 2. The semiconductor layer 23 of the electronic device 13 is electrically connected to the transparent electrode 2.

[0045] The insulating film 3 is a film containing an insulating material provided on the transparent electrode 2. The insulating film 3 is at least partially electrically conductive. The thickness direction of the insulating film 3 is the stacking direction of the insulating film 3, the liquid crystal layer 20, the light-emitting layer 22, or the semiconductor layer 23.

[0046] The insulating film 3 is in direct contact with the transparent electrode 2. The insulating film 3 is in direct contact with the surface of the transparent electrode 2 opposite to the substrate 1 side (the surface of the transparent electrode 2 facing the insulating film 3 side). Preferably, the transparent electrode 2 contains an oxide transparent conductive film on the side closest to the insulating film 3, and the insulating film 3 is in direct contact with the surface of the oxide transparent conductive film located closest to the insulating film 3 on the transparent electrode 2 opposite to the substrate 1 side (the surface of the oxide transparent conductive film located closest to the insulating film 3 on the transparent electrode 2 facing the insulating film 3 side).

[0047] It is preferable that the surface of the insulating film 3 facing the transparent electrode 2 is in direct contact with the transparent electrode 2. It is preferable that the entire surface of the insulating film 3 facing the transparent electrode 2 is in direct contact with the transparent electrode 2.

[0048] The insulating film 3 preferably covers 50% to 100% of the surface of the transparent electrode 2 opposite to the substrate 1 side, more preferably 95% to 100%, and even more preferably 99% to 100%.

[0049] The insulating film 3 can cover the entire surface of the transparent electrode 2 opposite to the substrate 1 side.

[0050] Electricity is thought to flow through the thinner portions of the insulating film 3 due to the tunneling effect. The insulating film 3 also includes thicker portions, and the thicker portions have lower electrical conductivity than the thinner portions. The thicker portions are thought to function as a barrier layer for the transparent electrode 2.

[0051] In order to provide electrical conductivity to the side of the laminate 10 opposite to the substrate 1 side, the thickness of the thin portion of the insulating film 3 is 0.1 [nm] or more and less than 3.0 [nm]. The thin portion of the insulating film 3 is defined as having a thickness in the range of 0.1 [nm] or more and less than 3.0 [nm]. The thickness of the insulating film 3 is determined by the method described in the first embodiment.

[0052] The average thickness of the thinnest portion of the insulating film 3 is preferably 0.2 nm or more and 2.8 nm or less, more preferably 0.5 nm or more and 2.5 nm or less, and even more preferably 0.5 nm or more and 2.0 nm or less.

[0053] The average of the total thickness of the insulating film 3 is called the average thickness of the insulating film 3. The average thickness of the insulating film 3 is preferably 1 nm or more and 15 nm or less, more preferably 1.5 nm or more and 12.5 nm or less, and even more preferably 2.5 nm or more and 10 nm or less.

[0054] The average thickness of the insulating film 3 is preferably 2 to 75 times the average thickness of the thinnest portion of the insulating film 3, more preferably 5 to 50 times, and even more preferably 5 to 25 times.

[0055] Preferably, the thickness distribution of the insulating film 3 has peaks in the range of 0.1 [nm] or more and less than 3.0 [nm], and in the range of 3.0 [nm] or more and 20 [nm] or less.

[0056] The insulating film 3 is preferably provided in such a way as to mitigate the height differences of at least some of the irregularities on the surface of the transparent electrode 2. For example, the average thickness of the insulating film 3 provided on the grain boundary portion of the transparent electrode 2 is preferably 1.5 times or more and 10 times or less the average thickness of the insulating film 3.

[0057] The thickness of the thickest portion of the insulating film 3 is 3.0 nm or more and 20 nm or less. The thickest portion of the insulating film 3 is defined as the range in which the thickness is 3.0 nm or more and 20 nm or less. The average thickness of the thickest portion of the insulating film 3 is preferably 3.5 nm or more and 18 nm or less, more preferably 4.0 nm or more and 15 nm or less, and even more preferably 4.0 nm or more and 10 nm or less.

[0058] The average thickness of the thicker portion of the insulating film 3 is preferably 1.1 times or more and 10 times or less the average thickness of the insulating film 3, more preferably 1.2 times or more and 8 times or less, and even more preferably 1.3 times or more and 5 times or less.

[0059] The insulating film 3 may have portions exceeding the thickness of its thickest portion. The maximum thickness of the insulating film 3, including the case where the insulating film 3 has portions exceeding the thickness of its thickest portion, is preferably 15 nm or more and 50 nm or less, more preferably 15 nm or more and 30 nm or less, and even more preferably 15 nm or more and 20 nm or less.

[0060] The minimum thickness of the insulating film 3 is preferably 0.1 nm or more and less than 3.0 nm.

[0061] The ratio of the thin portion of the insulating film 3 ([number of locations where the thickness of the insulating film 3 is 0.1 [nm] or more and less than 3.0 [nm] among the 90 locations of insulating film 3 described in the first embodiment] / 90) is preferably 10% or more and 90% or less, preferably 20% or more and 90% or less, and more preferably 30% or more and 90% or less.

[0062] The ratio of the thickness of the insulating film 3 to the thickness of the thicker portion ([number of locations where the thickness of the insulating film 3 is 3.0 [nm] or more and 20 [nm] or less out of the 90 locations of insulating film 3 described in the first embodiment] / 90) is preferably 10% or more and 90% or less, preferably 10% or more and 80% or less, and more preferably 10% or more and 70% or less.

[0063] The ratio of the thin portion of the insulating film 3 is preferably 0.3 to 5 times the ratio of the thick portion of the insulating film 3, and more preferably 0.5 to 4 times.

[0064] If the insulating film 3 contains a portion that is thicker than 20 nm, and / or if less than 100% of the surface of the transparent electrode 2 opposite to the substrate 1 side is covered with the insulating film 3, then the ratio of the thin portion of the insulating film 3 plus the ratio of the thick portion of the insulating film 3 will not equal 100%.

[0065] (Third embodiment) The third embodiment relates to a solar cell. A solar cell is a specific example of an electronic device. Figure 6 shows a schematic cross-sectional view of the solar cell 100 of the third embodiment. As shown in Figure 6, the solar cell 100 according to this embodiment has a substrate 1, a laminate 10 having a transparent electrode 2 which is the first electrode and an insulating film 3, a p-type light-absorbing layer 4, an n-type layer 5, and an n-electrode 6 which is the second electrode. The insulating film 3 is the insulating film 3 of the second embodiment. The transparent electrode 2 which is the first electrode is a p-electrode. Intermediate layers, not shown, may be included between the p-type light-absorbing layer 4 and the n-type layer 5, between the n-type layer 5 and the n-electrode 6, etc. Sunlight may be incident from either the n-electrode 6 side or the transparent electrode 2 side, but it is more preferable for it to be incident from the n-electrode 6 side. Since the solar cell 100 of the embodiment is a transmissive solar cell, it is preferable to use it on the top cell side (light incident side) of a multi-junction solar cell. The following description will be of the form shown in Figure 6, but the form in which the substrate 1 is provided on the n-electrode 6 side is similar, except that the position of the substrate 1 is different. In this embodiment, light is incident on the solar cell 100 from the n electrode 6 side toward the transparent electrode 2 side.

[0066] The solar cell 100 of this embodiment, when using transparent electrodes for the transparent electrode 2 and the n electrode 6, has high transmittance of light in the wavelength range of 700 nm to 1200 nm, and is a transparent solar cell with a reddish (reddish-brown), yellowish, or orange color.

[0067] The p-type light-absorbing layer 4 is a p-type semiconductor layer overall. The p-type light-absorbing layer 4 is provided on the transparent electrode 2. Preferably, the p-type light-absorbing layer 4 is in direct contact with the transparent electrode 2 and / or the insulating film 3. The p-type light-absorbing layer 4 is positioned between the insulating film 3 and the n-type layer 5. Not the entire surface of the p-type light-absorbing layer 4 facing the n-type layer 5, but only a portion of it, is in direct contact with the n-type layer 5. Preferably, the p-type light-absorbing layer 4 in direct contact with the n-type layer 5 forms a pn junction with the n-type layer 5. The p-type light-absorbing layer 4 mainly consists of a cuprous oxide compound. Preferably, the cuprous oxide compound has a cuprite-type structure.

[0068] The p-type light-absorbing layer 4 is preferably a semiconductor layer containing a cuprous oxide compound. The p-type light-absorbing layer 4 is preferably a polycrystalline form of the cuprous oxide compound. The p-type light-absorbing layer 4 may contain trace amounts of one or more cuprous oxide impurities selected from the group consisting of copper (Cu), copper oxide (CuO), and copper hydroxide (Cu(OH)2) as partial impurities.

[0069] When all elements except oxygen contained in the p-type light-absorbing layer 4 are considered to be 100%, the copper content in the p-type light-absorbing layer 4 is preferably 90% or more and less than 100%, preferably 95% or more and less than 100%, more preferably 98% or less and less than 100%, and even more preferably 99% or more and less than 100%.

[0070] When all elements except oxygen contained in the p-type light-absorbing layer 4 are considered to be 100%, the copper content in the p-type light-absorbing layer 4 is preferably 90% or more and 99.9%, preferably 95.0% or more and 99.9%, more preferably 98% or less and 99.9%, and even more preferably 99.0% or more and 99.9%.

[0071] Cuprous oxide compounds contain copper and oxygen, and optionally contain an element represented by M1. Preferably, the element represented by M1 is one or more elements selected from the group consisting of Cl, F, Br, I, Sn, Sb, Ag, Li, Na, K, Cs, Rb, Al, In, Zn, Mg, Ga, Si, Ge, N, P, B, Ti, Hf, Zr, and Ca.

[0072] The number of oxygen atoms in the cuprous oxide compound is preferably between 0.48 and 0.56, with the number of copper atoms being 1. A high oxygen-to-copper ratio is undesirable because it increases the proportion of copper oxide in the cuprous oxide compound, narrowing the band gap and reducing the transparency of the p-type light-absorbing layer 4. A low oxygen-to-copper ratio is also undesirable because it increases the amount of copper in the cuprous oxide compound, reducing its transparency. Furthermore, if the oxygen-to-copper ratio does not meet the above range, it becomes difficult for the cuprous oxide compound to have a cuprite-type structure.

[0073] Preferably, 95 wt% or more and less than 100 wt% of the p-type light-absorbing layer 4 is a cuprous oxide compound; more preferably, 98 wt% or more and less than 100 wt% of the p-type light-absorbing layer 4 is a cuprous oxide compound; and even more preferably, 99 wt% or more and 100 wt% or less is a cuprous oxide compound. 100 wt% of the p-type light-absorbing layer 4 can be composed of a cuprous oxide compound.

[0074] It is preferable that the p-type light-absorbing layer 4 contains few other phases and has good crystallinity, as this increases the light transmittance of the p-type light-absorbing layer 4. The band gap of the p-type light-absorbing layer 4 can be adjusted by means such as including elements other than Cu and O in the p-type light-absorbing layer 4. The band gap of the p-type light-absorbing layer 4 is preferably 2.0 [eV] or more and 2.2 [eV] or less. With a band gap in this range, in a multi-junction solar cell in which a solar cell using Si as the light-absorbing layer is used as the bottom cell and the solar cell of the embodiment is used as the top cell, sunlight can be efficiently utilized in both the top cell and the bottom cell. It is preferable that the p-type light-absorbing layer 4 contains Sn and / or Sb. The Sn and Sb in the p-type light-absorbing layer 4 may be added to the p-type light-absorbing layer 4 or may originate from the transparent electrode 2. The Ga contained in the p-type light-absorbing layer 4 is not contained in the raw materials for forming the p-type light-absorbing layer 4, but is Ga contained in the n-type layer 5 that has diffused into the p-type light-absorbing layer 4. If other elements are used during the deposition of the n-type layer 5, these elements may also diffuse into the p-type light-absorbing layer 4.

[0075] The composition ratio of the p-type light-absorbing layer 4 described above is the overall composition ratio of the p-type light-absorbing layer 4. Furthermore, it is preferable that the compound composition ratio of the p-type light-absorbing layer 4 described above is satisfied throughout the p-type light-absorbing layer 4.

[0076] The p-type light absorption layer 4 preferably has a p+ type (p-plus type) region on the transparent electrode 2 side.

[0077] It is preferable that the p-type light absorption layer 4 has a p-type (p-minus type) region on the n-type layer 5 side.

[0078] Preferably, the p-type light absorption layer 4 has a p-type (p-minus type) region on the n-type layer 5 side and a p+-type (p-plus type) region on the transparent electrode 2 side.

[0079] The composition of the p-type light-absorbing layer 4 is such that, when the thickness of the p-type light-absorbing layer 4 is d1, the layers are: the surface of the p-type light-absorbing layer 4 on the n-type layer 5 side, a depth of 0.1d1 (0.1 x d1) from the surface of the p-type light-absorbing layer 4 on the n-type layer 5 side toward the transparent electrode in two directions, a depth of 0.2d1 (0.2 x d1) from the surface of the p-type light-absorbing layer 4 on the n-type layer 5 side toward the transparent electrode in two directions, a depth of 0.3d1 (0.3 x d1) from the surface of the p-type light-absorbing layer 4 on the n-type layer 5 side toward the transparent electrode in two directions, and a depth of 0.4d1 (0.4 x d1) from the surface of the p-type light-absorbing layer 4 on the n-type layer 5 side toward the transparent electrode in two directions. This represents the average composition at the following depths: d1), 0.5d1 (0.5 x d1) from the surface of the p-type light absorption layer 4 on the n-type layer 5 side toward the transparent electrode 2, 0.6d1 (0.6 x d1) from the surface of the p-type light absorption layer 4 on the n-type layer 5 side toward the transparent electrode 2, 0.7d1 (0.7 x d1) from the surface of the p-type light absorption layer 4 on the n-type layer 5 side toward the transparent electrode 2, and 0.8d1 (0.8 x d1) and 0.9d1 (0.9 x d1) from the surface of the p-type light absorption layer 4 on the n-type layer 5 side toward the transparent electrode 2. In the case of SIMS, since elements of the n-type layer 5 are easily detected when the surface of the p-type light absorption layer 4 is analyzed, it is preferable to determine the average composition by analyzing the p-type light absorption layer 4 from the 0.1d1 point.

[0080] The p-type light-absorbing layer 4 is preferably formed by, for example, sputtering. Specifically, it is preferable to heat the member on which the transparent electrode 2 is formed on the substrate 1 to 300°C or higher and 1000°C or lower, with the oxygen partial pressure being in the range of 0.01 Pa or higher and 4.8 Pa or lower, and the deposition rate being in the range of 0.02 μm / min or higher and 20 μm / min or lower. From the viewpoint of forming a highly transparent, large-grained polycrystalline film, when the deposition rate is d, it is more preferable that the oxygen partial pressure is 0.20 x d Pa or higher and 1.00 x d Pa or lower (for example, k; in the case of high-temperature sputtering, 0.20 x d Pa or higher and 0.50 x d Pa or lower are preferable, and in the case of low-temperature sputtering, 0.55 x d Pa or higher and 1.00 x d Pa or lower are preferable). Furthermore, the heating temperature is more preferably 350°C or higher and 500°C or lower. The element M1 can be added during film formation.

[0081] The n-type layer 5 is an n-type semiconductor layer. The n-type layer 5 is disposed between the p-type light absorption layer 4 and the n electrode 6. The n-type layer 5 is preferably provided on the p-type light absorption layer 4. The n-type layer 5 is formed, for example, by the ALD method.

[0082] The n-type layer 5 preferably contains a compound (oxide) having Ga as a main component. In the n-type layer 5, other oxides may be mixed with the oxide having Ga as a main component, other elements may be doped into the oxide having Ga as a main component, or other oxides may be mixed with the oxide having Ga as a main component doped with other elements. The n-type layer 5 is a single layer or a multilayer. Among the metal elements contained in the n-type layer 5, it is preferable that Ga is 40 atomic% or more, and more preferably 50 atomic% or more. The Ga-containing metal element contained in the n-type layer 5 may be inclined from the p-type light absorption layer 4 side to the n electrode 6 side. When the n-type layer 5 is a multilayer semiconductor layer (for example, two layers), it is the first n-type layer and the second n-type layer from the p-type light absorption layer 4 side. It is preferable that the element represented by M2 contained in the first n-type layer is less than the element represented by M2 contained in the second n-type layer.

[0083] The n-type layer 5 preferably contains an oxide containing an element represented by M2 and Ga. The oxide having Ga as a main component is, for example, an oxide containing an element represented by M2 and Ga. The n-type layer 5 preferably contains an oxide containing an element represented by M2 and Ga, which is one or more elements selected from the group consisting of H, Sn, Sb, Cu, Ag, Li, Na, K, Cs, Rb, Al, In, Zn, Mg, Si, Ge, N, B, Ti, Hf, Zr, Ca, Ce, La, Pr, and Nd. In the case of the multilayer n-type layer 5, for example, the n-type layer 5 used for the first n-type layer preferably contains 90 wt% or more and 100 wt% or less of an oxide containing an element represented by M2 and Ga, which is one or more elements selected from the group consisting of H, Sn, Sb, Cu, Ag, Li, Na, K, Cs, Rb, Al, In, Zn, Mg, Si, Ge, N, B, Ti, Hf, Zr, Ca, Ce, La, Pr, and Nd. The compound having Ga as a main component of the n-type layer 5 has an average composition of Ga h1 M2 i1 O j1It is preferable that the oxide contains M2 and Ga, as represented by [formula]. It is preferable that h1, i1, and j2 satisfy 1.8≦h1≦2.1, 0.0≦i1≦0.2, and 2.9≦j1≦3.1. In the case of a multilayer n-type layer 5, for example, the n-type layer used in the second n-type layer is preferably Zn-doped tin oxide.

[0084] It is preferable that 90 wt% to 100 wt% of the n-type layer 5 is an oxide containing M2 and Ga. It is more preferable that 95 wt% to 100 wt% of the n-type layer 5 is an oxide containing M2 and Ga. It is even more preferable that 98 wt% to 100 wt% of the n-type layer 5 is a compound represented by an oxide containing M2 and Ga. The Cu contained in the n-type layer 5 is not contained in the raw materials for forming the n-type layer 5, but is Cu contained in the p-type light absorption layer 4 that has diffused into the n-type layer 5. If other elements are also used when forming the p-type light absorption layer 4, these elements may also diffuse into the n-type layer 5.

[0085] The thickness of the n-type layer 5 is typically between 3 nm and 100 nm. If the thickness of the n-type layer 5 is less than 3 nm, leakage current may occur if the coverage of the n-type layer 5 is poor, which may degrade the performance. If the coverage is good, the thickness is not limited to the above. If the thickness of the n-type layer 5 exceeds 50 nm, performance degradation may occur due to excessively high resistance of the n-type layer 5, or a decrease in short-circuit current may occur due to decreased transmittance. Therefore, the thickness of the n-type layer 5 is more preferably between 3 nm and 20 nm, and even more preferably between 5 nm and 20 nm.

[0086] The n-electrode 6 is an electrode on the n-type layer 5 side that is light-transmitting to visible light. Preferably, the n-electrode 6 is provided on the n-type layer 5. An intermediate layer (not shown) can be provided between the n-type layer 5 and the n-electrode 6. Preferably, an oxide transparent conductive film is used for the n-electrode 6. Preferably, the oxide transparent conductive film used for the n-electrode 6 is one or more semiconductor conductive films selected from the group consisting of indium tin oxide, aluminum-doped zinc oxide, boron-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, titanium-doped indium oxide, indium gallium zinc oxide, and hydrogen-doped indium oxide. The dopant to the film such as tin oxide is not particularly limited as long as it is one or more selected from the group consisting of In, Si, Ge, Ti, Cu, Sb, Nb, Ta, W, Mo, F, and Cl. The n-electrode 6 may include mesh or line-shaped electrodes in order to reduce the resistance of the oxide transparent conductive film. The mesh or line-shaped electrodes are not particularly limited to Mo, Au, Cu, Ag, Al, Ta, or W. Graphene can also be used for the n electrode 6. It is preferable to laminate the graphene with silver nanowires.

[0087] The thickness of the n electrode 6 can be determined by cross-sectional observation with an electron microscope or by a step gauge. There are no particular limitations, but it is typically between 50 nm and 2 μm.

[0088] The n electrode 6 is preferably formed by a method such as ALD or sputtering.

[0089] Note that the composition of compounds in the p-type light-absorbing layer 4 and n-type layer 5 is the average composition of the entire p-type light-absorbing layer 4 and n-type layer 5 unless otherwise specified. For example, the composition of each layer can be determined by analyzing the analysis spots (A1-A9) in Figure 2 using, for example, secondary ion mass spectrometry (SIMS).

[0090] (Fourth Embodiment) The fourth embodiment relates to a multi-junction solar cell. Figure 7 shows a conceptual cross-sectional view of the multi-junction solar cell of the fourth embodiment. The multi-junction solar cell 200 in Figure 7 has a solar cell (first solar cell) 100 of the third embodiment and a second solar cell 201 on the light incident side. The band gap of the light absorption layer of the second solar cell 201 is smaller than that of the p-type light absorption layer 4 of the solar cell 100 of the third embodiment. Note that the multi-junction solar cell 200 of the embodiment also includes solar cells formed by joining three or more solar cells.

[0091] Since the band gap of the p-type light-absorbing layer (cuprous oxide) 3 of the first solar cell 100 in the third embodiment is approximately 2.0 [eV] to 2.2 [eV], it is preferable that the band gap of the light-absorbing layer of the second solar cell 201 is 1.0 [eV] to 1.6 [eV]. The light-absorbing layer of the second solar cell 201 is preferably one or more compound semiconductor layers selected from the group consisting of CIGS-type and CdTe-type semiconductors with a high In content, crystalline silicon, and a perovskite-type compound.

[0092] (Fifth embodiment) The fifth embodiment relates to a solar cell module. Figure 8 shows a perspective view of the solar cell module 300 of the fifth embodiment. The solar cell module 300 in Figure 8 is a solar cell module in which a first solar cell module 301 and a second solar cell module 302 are stacked. The first solar cell module 301 is on the light incident side and uses the solar cell 100 of the third embodiment. It is preferable to use the second solar cell 201 in the second solar cell module 302.

[0093] Figure 9 shows a cross-sectional view of the solar cell module 300. Figure 9 shows the structure of the first solar cell module 301 in detail, but does not show the structure of the second solar cell module 302. In the second solar cell module 302, the structure of the solar cell module is selected as appropriate depending on the light absorption layer of the solar cell used. The solar cell module 300 in Figure 9 includes multiple submodules 303 enclosed by dashed lines, in which multiple solar cells 100 are arranged horizontally and electrically connected in series by wiring 304. Multiple submodules 303 are electrically connected in parallel or in series. Adjacent submodules 303 are electrically connected by busbars 305.

[0094] Adjacent solar cells 100 are connected by wiring 304 between the upper n-electrode 6 and the lower transparent electrode 2. The solar cell 100 of the third embodiment also has a substrate 1, a transparent electrode 2, an insulating film 3, a p-type light-absorbing layer 4, an n-type layer 5, and an n-electrode 6, similar to the solar cell 100 of the third embodiment. It is preferable that both ends of the solar cell 100 in the submodule 303 are connected to a busbar 305, and the busbar 305 is configured to electrically connect multiple submodules 303 in parallel or series and adjust the output voltage with the second solar cell module 302. Note that the connection configuration of the solar cell 100 shown in the third embodiment is just one example, and the solar cell module can be configured with other connection configurations.

[0095] (Sixth Embodiment) The sixth embodiment relates to a photovoltaic power generation system. The solar cell module of the sixth embodiment can be used as a generator to generate electricity in the photovoltaic power generation system of the sixth embodiment. The photovoltaic power generation system of the embodiment generates electricity using a solar cell module, and specifically includes a solar cell module that generates electricity, means for converting the generated electricity into power, and energy storage means for storing the generated electricity or a load for consuming the generated electricity. Figure 10 shows a configuration diagram of the photovoltaic power generation system 400 of the embodiment. The photovoltaic power generation system of Figure 10 includes a solar cell module 401 (300), a converter 402, a storage battery 403, and a load 404. Either the storage battery 403 or the load 404 may be omitted. The load 404 may also be configured to utilize the electrical energy stored in the storage battery 403. The converter 402 is a device that includes a circuit or element that performs power conversion such as voltage transformation or DC-AC conversion, such as a DC-DC converter, DC-AC converter, or AC-AC converter. The converter 402 can be configured in a way that is suitable for the generated voltage and the configuration of the battery 403 and load 404.

[0096] The solar cells in the light-receiving submodule 303 included in the solar cell module 401 generate electricity, and this electrical energy is converted by the converter 402 and stored in the battery 403 or consumed by the load 404. It is preferable to add a solar cell module 401 with a solar tracking drive device to keep the solar cell module 401 facing the sun, a light concentrator to concentrate sunlight, and devices to improve power generation efficiency.

[0097] The solar power generation system 400 is preferably used in real estate such as residences, commercial facilities, and factories, or in movable property such as vehicles, aircraft, and electronic equipment. By using the solar cells with excellent conversion efficiency of the embodiment in the solar cell module, an increase in power generation can be expected.

[0098] An example of the use of the solar power generation system 400 is shown in a vehicle. Figure 11 shows a conceptual diagram of the vehicle 500. The vehicle 500 in Figure 11 has a vehicle body 501, a solar cell module 502, a power converter 503, a storage battery 504, a motor 505, and tires (wheels) 506. The electricity generated by the solar cell module 502, which is installed on the top of the vehicle body 501, is converted by the power converter 503 and charged in the storage battery 504, or the electricity is consumed by a load such as the motor 505. The vehicle 500 can be moved by using the electricity supplied from the solar cell module 502 or the storage battery 504 to rotate the tires (wheels) 506 with the motor 505. The solar cell module 502 may not be a multi-junction type, but may consist only of a first solar cell module equipped with the solar cell 100 of the first embodiment. When a transparent solar cell module 502 is used, it is also preferable to use the solar cell module 502 as a power-generating window on the side of the vehicle body 501 in addition to the top of the vehicle body 501.

[0099] As an example of the use of the solar power generation system 400, a drone (quadcopter) is shown. The drone uses a solar cell module 401. The configuration of the drone according to this embodiment will be briefly explained using the schematic diagram of the drone 600 in Figure 12. The drone 600 has a solar cell module 401, an airframe 601, a motor 602, rotor blades 603, and a control unit 604. The solar cell module 401, motor 602, rotor blades 603, and control unit 604 are arranged on the airframe 601. The control unit 604 converts and adjusts the power output from the solar cell module 401. The motor 602 rotates the rotor blades 603 using the power output from the solar cell module 401. By using the drone 600 with the solar cell module 401 of this embodiment, a drone that can fly using more power is provided.

[0100] The present invention will be described more specifically below based on examples, but the present invention is not limited to the following examples.

[0101] (Example A) (Example A1) On a white glass substrate 1, ITO (In:Sn=80:20, film thickness 150 [nm]) and ATO (Sn:Sb=98:2, film thickness 100 [nm]) are deposited on the upper surface of the back side of the transparent electrode 2, which is in contact with the glass. The thickness of the white glass substrate 1 is 0.5 [mm]. On the ATO, an insulating film 3 is deposited over the entire surface of the transparent electrode 2 by sputtering so that the average film thickness is 10 [nm] with a ratio of SiO2:Na2O:CaO=7:2:1. Then, a Cu2O layer with a thickness of 6 [μm] is deposited on the insulating film 3 as a p-type light absorption layer 4 by sputtering in an oxygen and argon gas atmosphere. After the deposition of the p-type light absorption layer 4, a Ga2O3 film with a thickness of 10 [nm] is deposited as an n-type layer 5 (first n-layer). A 14 nm thick ZnSnO (Zn:Sn=80:20) film is deposited on the Ga2O3 as the second n layer. Then, a 0.1 μm thick AZO (ZnO:Al) film is deposited as the n electrode 6 to obtain solar cell 100.

[0102] A solar simulator simulating an AM1.5G light source is used, and the light intensity is adjusted to achieve 1 sun using a reference Si cell under that light source. Measurements are taken under atmospheric pressure, and the temperature in the measurement room is 25°C. The voltage is swept, and the short-circuit current density Jsc (current divided by cell area) is measured. When the horizontal axis is voltage and the vertical axis is current density, the point where the curve intersects the horizontal axis is the open-circuit voltage Voc. On the measurement curve, the product of voltage and short-circuit current density is multiplied, and the points where they are maximum are Vmpp and Jmpp (maximum power points), respectively. Then the fill factor can be calculated from FF = (Vmpp * Jmpp) / (Voc * Jsc). The conversion efficiency can also be calculated from Eff. = Voc * Jsc * FF.

[0103] Regarding light transmittance, if the light transmittance of Example A1 in the wavelength range of 700 nm to 1000 nm is 101% or more compared to the light transmittance of the comparison target in the same wavelength range of 700 nm to 1000 nm, it is evaluated as A; if it is 95% or more but less than 101%, it is evaluated as B; and if it is less than 95%, it is evaluated as C.

[0104] Regarding Jsc, if the Jsc of Example A1 is 1.04 times or more than the Jsc of the comparison target, it is evaluated as A; if it is 1.00 times or more but less than 1.04 times, it is evaluated as B; and if it is less than 1.00 times, it is evaluated as C.

[0105] Regarding FF, if the FF of Example A1 is 1.01 times or more than the FF of the comparison target, it is evaluated as A; if it is 1.00 times or more but less than 1.01 times, it is evaluated as B; and if it is less than 1.00 times, it is evaluated as C.

[0106] Regarding conversion efficiency, if the conversion efficiency of Example A1 is 1.05 times or more than the conversion efficiency of the comparison target, it is evaluated as A; if it is 1.00 times or more but less than 1.05 times the conversion efficiency of the comparison target, it is evaluated as B; and if it is less than 1.00 times the conversion efficiency of the comparison target, it is evaluated as C.

[0107] (Comparative Example A1) On a white glass substrate 1, ITO (In:Sn=80:20, film thickness 150 [nm]) and ATO (Sn:Sb=98:2, film thickness 100 [nm]) are deposited on the upper surface of the side in contact with the glass as the transparent electrode 2 on the back side. The thickness of the white glass substrate 1 is 0.5 mm. On the ATO, a Cu2O layer with a thickness of 6 [μm] is deposited as a p-type light absorption layer 4 by sputtering in an oxygen and argon gas atmosphere. After the deposition of the p-type light absorption layer 4, a Ga2O3 film with a thickness of 10 [nm] is deposited as an n-type layer 5 (first n-layer). On the Ga2O3, a ZnSnO (Zn:Sn=80:20) film with a thickness of 14 [nm] is deposited as a second n-layer. Then, an AZO (ZnO:Al) film with a thickness of 0.1 [μm] is deposited as the n-electrode 6 to obtain a solar cell 100. Then, the solar cell of Comparative Example A1 is evaluated in the same manner as in Example A1.

[0108] (Example A2) A solar cell is obtained in the same manner as in Example A1, except that the transparent electrode 2 is formed so that its film thickness is 170 nm (ITO, 70 nm, ATO, 100 nm). Then, the solar cell of Example A2 is evaluated in the same manner as in Example A1. (Example A3) A solar cell is obtained in the same manner as in Example A1, except that the transparent electrode 2 is formed to have a film thickness of 155 nm (ITO, 55 nm, ATO, 100 nm). Then, the solar cell of Example A2 is evaluated in the same manner as in Example A1. (Example A4) A solar cell is obtained in the same manner as in Example A1, except that the transparent electrode 2 is formed to have a film thickness of 140 nm (ITO, 40 nm, ATO, 100 nm). Then, the solar cell of Example A2 is evaluated in the same manner as in Example A1. (Example A5) A solar cell is obtained in the same manner as in Example A1, except that the transparent electrode 2 is formed to have a film thickness of 115 nm (ITO, 55 nm, ATO, 60 nm). Then, the solar cell of Example A2 is evaluated in the same manner as in Example A1.

[0109] (Comparative example A2) A solar cell is obtained in the same manner as in Comparative Example A1, except that the transparent electrode 2 is formed to have a film thickness of 170 nm (ITO, 70 nm, ATO, 100 nm). Then, the solar cell of Comparative Example A2 is evaluated in the same manner as in Comparative Example A1.

[0110] (Example A6) A solar cell is obtained in the same manner as in Example A1, except that Al2O3 is deposited as the insulating film 3 by sputtering. Then, the solar cell of Example A3 is evaluated in the same manner as in Example A1.

[0111] (Example A7) A solar cell is obtained in the same manner as in Example A2, except that Al2O3 is deposited as the insulating film 3 by sputtering. Then, the solar cell of Example A4 is evaluated in the same manner as in Example A2.

[0112] (Example A8) A solar cell is obtained in the same manner as in Example A1, except that SiO2 is deposited as the insulating film 3 by sputtering. Then, the solar cell of Example A5 is evaluated in the same manner as in Example A1.

[0113] (Example A9) A solar cell is obtained in the same manner as in Example A2, except that SiO2 is deposited as the insulating film 3 by sputtering. Then, the solar cell of Example A6 is evaluated in the same manner as in Example A2.

[0114] The evaluation results of the solar cell of Example A are shown in the table in Figure 13. The insulating film 3 of Examples A1 to A6 all include both thin and thick portions, and the coverage rate is between 50% and 100%. Figures 14 and 15 show TEM images of the solar cell of Example 1. The TEM image in Figure 14 shows the thin portion of the insulating film 3. The TEM image in Figure 15 shows the thick portion of the insulating film 3.

[0115] As shown in the table in Figure 13, it can be seen that all solar cells with insulating film 3 have improved conversion efficiency. Regarding solar cells without insulating film 3, Comparative Example A1 (transparent electrode 2 with a thickness of 250 [nm]) has a higher conversion efficiency than Comparative Example A2 (transparent electrode with a thickness of 170 [nm]), but by providing insulating film 3, it is possible to obtain a solar cell with superior conversion efficiency even with a thinner transparent electrode 2. Because insulating film 3 is provided, the sheet resistance of the laminate of the transparent electrode 2 and insulating film 3 of the solar cell is lower than that of the transparent electrode 2 of the solar cell without insulating film 3, so the Jsc of the solar cell in the example is better than that of the comparative example. In addition, since the FF is improved by reducing the thickness of the transparent electrode 2, the conversion efficiency of solar cells with a thin transparent electrode 2 and insulating film 3 is effectively improved. In Example A, soda-lime glass, Al2O3, and SiO2 were used as insulating film 3, and the effect of insulating film 3 was confirmed for each material.

[0116] (Example B) (Example B1) On a white glass substrate 1, ITO (In:Sn=80:20, 150 nm thick) is deposited on the upper surface of the side in contact with the glass as the transparent electrode 2 on the back side. The thickness of the white glass substrate 1 is 0.5 mm. On the ITO, an insulating film 3 is deposited over the entire surface of the transparent electrode 2 by sputtering so that the average film thickness is 10 nm, with SiO2:Na2O:CaO = 7:2:1. Then, a 6 μm thick Cu2O layer is deposited on the insulating film 3 as a p-type light absorption layer 4 by sputtering in an oxygen and argon gas atmosphere. After the deposition of the p-type light absorption layer 4, a 10 nm thick Ga2O3 film is deposited as an n-type layer 5 (first n-layer). On the Ga2O3, a 14 nm thick ZnSnO (Zn:Sn=80:20) film is deposited as a second n-layer. Then, a 0.1 [μm] thick AZO (ZnO:Al) film is deposited as the n electrode 6 to obtain solar cell 100. The solar cell of Example B2 is then evaluated in the same manner as in Example A1.

[0117] (Comparative Example B1) On a white glass substrate 1, ITO (In:Sn=80:20, film thickness 150 [nm]) is deposited on the upper surface of the side in contact with the glass as the transparent electrode 2 on the back side. The thickness of the white glass substrate 1 is 0.5 [mm]. On the ITO, a Cu2O layer with a thickness of 6 [μm] is deposited as a p-type light absorption layer 4 by sputtering in an oxygen and argon gas atmosphere. After the deposition of the p-type light absorption layer 4, a Ga2O3 film with a thickness of 10 [nm] is deposited as an n-type layer 5 (first n-layer). On the Ga2O3, a ZnSnO (Zn:Sn=80:20) film with a thickness of 14 [nm] is deposited as a second n-layer. Then, an AZO (ZnO:Al) film with a thickness of 0.1 [μm] is deposited as the n-electrode 6 to obtain a solar cell 100. The solar cell of Example B2 is then evaluated in the same manner as in Example A1.

[0118] (Example B2) A solar cell is obtained in the same manner as in Example B1, except that Al2O3 is deposited as the insulating film 3 by sputtering. Then, the solar cell of Example B2 is evaluated in the same manner as in Example A1.

[0119] (Example B3) A solar cell is obtained in the same manner as in Example B1, except that SiO2 is deposited as the insulating film 3 by sputtering. Then, the solar cell of Example B3 is evaluated in the same manner as in Example A1.

[0120] The evaluation results of the solar cell in Example B are shown in the table in Figure 16. The insulating film 3 in Examples B1 to B3 all include both thin and thick portions, and the coverage rate is between 50% and 100%. As shown in the table in Figure 16, even when a single film of ITO is used for the transparent electrode 2, the conversion efficiency is improved by providing the insulating film 3, similar to Example A.

[0121] (Example C) (Example C1) On a white glass substrate 1, ITO (In:Sn=80:20, film thickness 70 [nm]) and ATO (Sn:Sb=98:2, film thickness 100 [nm]) are deposited on the upper surface of the back side of the transparent electrode 2, which is in contact with the glass. The thickness of the white glass substrate 1 is 0.5 [mm]. On the ATO, an insulating film 3 is deposited over the entire surface of the transparent electrode 2 by sputtering so that the average film thickness is 10 [nm] with a ratio of SiO2:Na2O:CaO=7:2:1. Then, a Cu2O layer with a thickness of 6 [μm] is deposited on the insulating film 3 as a p-type light absorption layer 4 by sputtering in an oxygen and argon gas atmosphere. After the deposition of the p-type light absorption layer 4, a Ga2O3 film with a thickness of 10 [nm] is deposited as an n-type layer 5 (first n-layer). A 14 nm thick ZnSnO (Zn:Sn=80:20) film is deposited on the Ga2O3 as the second n layer. Then, a 0.1 μm thick AZO (ZnO:Al) film is deposited as the n electrode 6 to obtain solar cell 100.

[0122] (Example C2) A solar cell is obtained in the same manner as in Example C1, except that the insulating film 3 is deposited on ATO by sputtering so that the average film thickness is 8 nm, SiO2:Na2O:CaO = 7:2:1.

[0123] (Example C3) A solar cell is obtained in the same manner as in Example C1, except that the insulating film 3 is deposited on ATO by sputtering so that the average film thickness is 5 nm, SiO2:Na2O:CaO = 7:2:1.

[0124] (Example C4) A solar cell is obtained in the same manner as in Example C1, except that the insulating film 3 is deposited on ATO by sputtering so that the average film thickness is 3 [nm] SiO2:Na2O:CaO = 7:2:1.

[0125] (Example C5) A solar cell is obtained in the same manner as in Example C1, except that the insulating film 3 is deposited on ATO by sputtering so that the average film thickness is 1.5 nm, SiO2:Na2O:CaO = 7:2:1.

[0126] (Comparative Example C0) A solar cell is obtained in the same manner as in Example C1, except that the insulating film 3 is not deposited.

[0127] (Example C6) A solar cell is obtained in the same manner as in Example C1, except that the insulating film 3 is deposited on ATO by sputtering so that the average film thickness is 1 nm SiO2:Na2O:CaO = 7:2:1.

[0128] (Comparative Example C1) A solar cell is obtained in the same manner as in Example C1, except that the insulating film 3 is deposited on ATO by sputtering so that the average film thickness is 100 nm, SiO2:Na2O:CaO = 7:2:1.

[0129] The evaluation results for the solar cell of Example C are shown in the table in Figure 17. As shown in the table in Figure 17, the conversion efficiency improves when the thickness of the insulating film 3 is in the range of 1 nm to 10 nm. Furthermore, when the thickness of the insulating film 3 becomes 100 nm, the transparent electrode 2 is sandwiched between the thick insulating film 3 and the insulating substrate, causing the solar cell to cease functioning.

[0130] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and in the implementation stage, the components can be modified and implemented without departing from the gist of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, components from different embodiments may be appropriately combined, as in the modified examples.

[0131] In the specification, some elements are indicated only by their element symbols.

[0132] The following is a technical proposal for an embodiment. Technical proposal 1 circuit board and A transparent electrode provided on the substrate, An insulating film is provided on the transparent electrode and covers 50% to 100% of the surface of the transparent electrode opposite to the substrate side, and is thinner than the substrate. A laminate having the following characteristics. Technical proposal 2 The thickness of the insulating film is 1 nm or more and 50 nm or less. The laminate according to Technical Proposal 1, wherein the average thickness of the insulating film is 1 nm or more and 30 nm or less. Technical proposal 3 The average value of the thickness of the insulating film is 10 times the thickness of the substrate. -8 more than 10 times -3 The laminate described in Technical Proposal 1 is less than twice the original size. The insulating film is in direct contact with the transparent electrode, The laminate according to Technical Proposal 1, wherein the insulating film comprises one or more selected from the group consisting of SiO2, Al2O3, SiN, SiON, and MgO. Technical proposal 4 The laminate according to Technical Proposal 2, wherein the entire surface of the insulating film facing the transparent electrode is in direct contact with the transparent electrode. Technical proposal 5 The insulating film is a laminate according to Technical Proposal 2, comprising SiO2, Na2O, and CaO. Technical proposal 6 The insulating film is amorphous, as described in Technical Proposal 1. Technical proposal 7 The laminate according to Technical Proposal 1, wherein the insulating film covers 95% to 100% of the surface of the transparent electrode opposite to the substrate side. Technical proposal 8 The insulating film comprises one or more selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, SiN, SiON, and MgO. The laminate according to Technical Proposal 7, wherein the total amount of one or more elements selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, SiN, SiON, and MgO contained in the insulating film is 70 [wt%] or more and 100 [wt%] or less of the insulating film. Technical proposal 9 The insulating film comprises one or more selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, SiN, SiON, and MgO. The total amount of one or more elements selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, SiN, SiON, and MgO in the insulating film is 95 [wt%] or more and 100 [wt%] or less of the insulating film. The laminate according to Technical Proposal 7, wherein the total amount of one or more elements selected from the group consisting of SiO2, Al2O3, SiN, SiON, and MgO contained in the insulating film is 50 [wt%] or more and 100 [wt%] or less of the insulating film. Technical proposal 10 The laminate according to Technical Proposal 1, wherein the insulating film is soda-lime glass. Technical proposal 11 The laminate according to Technical Proposal 1, wherein the insulating film covers 99% to 100% of the surface of the transparent electrode opposite to the substrate side. Technical proposal 12 The laminate according to Technical Proposal 1, wherein the surface of the insulating film opposite to the surface facing the transparent electrode is exposed. Technical proposal 13 A laminate described in any one of Technical Proposals 1, 3, or 11, A liquid crystal layer, an emissive layer, or a semiconductor layer provided on the insulating film of the laminate, It has, The semiconductor layer is an electronic device containing a compound semiconductor. Technical proposal 14 A laminate described in any one of Technical Proposals 1, 3, or 11, A p-type light-absorbing layer provided on the insulating film of the laminate, An n-type layer provided on the aforementioned p-type light absorption layer, An n-electrode provided on the n-type layer, It has, The p-type light-absorbing layer is a solar cell containing a compound semiconductor. Technical proposal 15 The insulating film has a thin portion and a thick portion, The thickness of the thin portion of the insulating film is 0.1 [nm] or more and less than 3.0 [nm]. The thickness of the thicker portion of the insulating film is 3.0 nm or more and 20 nm or less. The maximum thickness of the insulating film is 15 nm or more and 50 nm or less. The proportion of the thin portion of the insulating film is 10% or more and 90% or less. The ratio of the thick portion of the insulating film is 10% or more and 90% or less. The solar cell according to Technical Proposal 14, wherein the average thickness of the insulating film is 1 nm or more and 15 nm or less. Technical proposal 16 The entire surface of the insulating film facing the transparent electrode is in direct contact with the transparent electrode. The insulating film has a thin portion and a thick portion, The thickness of the thin portion of the insulating film is 0.1 [nm] or more and less than 3.0 [nm]. The thickness of the thicker portion of the insulating film is 3.0 nm or more and 20 nm or less. The maximum thickness of the insulating film is 15 nm or more and 50 nm or less. The proportion of the thin portion of the insulating film is 10% or more and 90% or less. The ratio of the thick portion of the insulating film is 10% or more and 90% or less. The average thickness of the insulating film is between 1 nm and 15 nm. The insulating film is amorphous, The insulating film covers 95% to 100% of the surface of the transparent electrode opposite to the substrate side. The insulating film comprises one or more selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, SiN, SiON, and MgO. The total amount of one or more elements selected from the group consisting of SiO2, Na2O, CaO, B2O3, Al2O3, SiN, SiON, and MgO in the insulating film is 95 [wt%] or more and 100 [wt%] or less of the insulating film. The solar cell according to Technical Proposal 14 or 15, wherein the total amount of one or more elements selected from the group consisting of SiO2, Al2O3, SiN, SiON, and MgO contained in the insulating film is 50 [wt%] or more and 100 [wt%] or less of the insulating film. Technical proposal 17 The aforementioned p-type light-absorbing layer is a solar cell according to any one of the technical proposals 14 to 16, mainly composed of a cuprous oxide compound. Technical proposal 18 A multi-junction solar cell using a solar cell described in any one of Technical Proposals 14 to 17. Technical proposal 19 A solar cell module using a solar cell described in any one of Technical Proposals 14 to 17. Technical proposal 20 A photovoltaic power generation system that generates electricity using the solar cell modules described in Technical Proposal 19. [Explanation of Symbols]

[0133] 1: Circuit board 2:Transparent electrode 3: Insulating film 4: p-type light-absorbing layer 5:n-type layer 6 :n electrode 10: Laminate 11:Electronic equipment 12:Electronic equipment 13:Electronic equipment 20: Liquid crystal layer 21: Electrode 22: Emitting layer 23: Semiconductor layer 100: Solar cell 200: Multijunction solar cell 201:Second solar cell 300: Solar cell module 301: First solar cell module 302: Second solar cell module 303: Submodule 304: Wiring 305: Bus bar 400: Solar power generation system 401: Solar cell module 402: Converter 403: Storage Battery 404: Load 500: Vehicle 501: Vehicle body 502: Solar cell module 503: Power converter 504: Storage Battery 505: Motor 600: Drone 601: Aircraft frame 602: Motor 603: Rotary blade 604: Control Unit

Claims

1. circuit board and A transparent electrode provided on the substrate, An insulating film is provided on the transparent electrode and covers 50% to 100% of the surface of the transparent electrode opposite to the substrate side, and is thinner than the substrate. A laminate having the following characteristics.

2. The thickness of the insulating film is 1 nm or more and 50 nm or less. The laminate according to claim 1, wherein the average thickness of the insulating film is 1 nm or more and 30 nm or less.

3. The average value of the thickness of the insulating film is 10 times the thickness of the substrate. －８ more than 10 times －３ The laminate according to claim 1, wherein the number of times is less than or equal to the original number. The insulating film is in direct contact with the transparent electrode, The insulating film is SiO ２ Al ２ O ３ The laminate according to claim 1, comprising one or more selected from the group consisting of SiN, SiON, and MgO.

4. The laminate according to claim 2, wherein the entire surface of the insulating film facing the transparent electrode is in direct contact with the transparent electrode.

5. The insulating film is SiO ２ Na ２ The laminate according to claim 2, comprising O and CaO.

6. The laminate according to claim 1, wherein the insulating film is amorphous.

7. The laminate according to claim 1, wherein the insulating film covers 95% to 100% of the surface of the transparent electrode opposite to the substrate side.

8. The insulating film is SiO ２ , Na ２ O, CaO, B ２ O ３ , Al ２ O ３ and includes one or more selected from the group consisting of SiN, SiON, and MgO. The SiO contained in the insulating film ２ Na ２ O, CaO, B ２ O ３ Al ２ O ３ The laminate according to claim 7, wherein the total amount of one or more elements selected from the group consisting of SiN, SiON, and MgO is 70 [wt%] or more and 100 [wt%] or less of the insulating film.

9. The insulating film is SiO ２ Na ２ O, CaO, B ２ O ３ Al ２ O ３ It includes one or more selected from the group consisting of SiN, SiON, and MgO, The SiO contained in the insulating film ２ Na ２ O, CaO, B ２ O ３ Al ２ O ３ The total amount of one or more elements selected from the group consisting of SiN, SiON, and MgO is 95 [wt%] or more and 100 [wt%] or less of the insulating film. The SiO contained in the insulating film ２ Al ２ O ３ The laminate according to claim 7, wherein the total amount of one or more elements selected from the group consisting of SiN, SiON, and MgO is 50 [wt%] or more and 100 [wt%] or less of the insulating film.

10. The laminate according to claim 1, wherein the insulating film is soda-lime glass.

11. The laminate according to claim 1, wherein the insulating film covers 99% to 100% of the surface of the transparent electrode opposite to the substrate side.

12. The laminate according to claim 1, wherein the surface of the insulating film opposite to the surface facing the transparent electrode is exposed.

13. A laminate according to any one of claims 1, 3 to 11, A liquid crystal layer, an emissive layer, or a semiconductor layer provided on the insulating film of the laminate, It has, The semiconductor layer is an electronic device containing a compound semiconductor.

14. A laminate according to any one of claims 1, 3 to 11, A p-type light-absorbing layer provided on the insulating film of the laminate, An n-type layer provided on the p-type light absorbing layer, An n electrode provided on the n-type layer, It has, The p-type light-absorbing layer is a solar cell containing a compound semiconductor.

15. The insulating film has a thin portion and a thick portion, The thickness of the thin portion of the insulating film is 0.1 [nm] or more and less than 3.0 [nm]. The thickness of the thicker portion of the insulating film is 3.0 nm or more and 20 nm or less. The maximum thickness of the insulating film is 15 nm or more and 50 nm or less. The proportion of the thin portion of the insulating film is 10% or more and 90% or less. The ratio of the thick portion of the insulating film is 10% or more and 90% or less. The solar cell according to claim 14, wherein the average value of the thickness of the insulating film is 1 nm or more and 15 nm or less.

16. The entire surface of the insulating film facing the transparent electrode is in direct contact with the transparent electrode. The insulating film has a thin portion and a thick portion, The thickness of the thin portion of the insulating film is 0.1 [nm] or more and less than 3.0 [nm]. The thickness of the thicker portion of the insulating film is 3.0 nm or more and 20 nm or less. The maximum thickness of the insulating film is 15 nm or more and 50 nm or less. The proportion of the thin portion of the insulating film is 10% or more and 90% or less. The ratio of the thick portion of the insulating film is 10% or more and 90% or less. The average thickness of the insulating film is 1 nm or more and 15 nm or less. The insulating film is amorphous, The insulating film covers 95% to 100% of the surface of the transparent electrode opposite to the substrate side. The insulating film is SiO ２ Na ２ O, CaO, B ２ O ３ Al ２ O ３ It includes one or more selected from the group consisting of SiN, SiON, and MgO, The SiO contained in the insulating film ２ Na ２ O, CaO, B ２ O ３ Al ２ O ３ The total amount of one or more elements selected from the group consisting of SiN, SiON, and MgO is 95 [wt%] or more and 100 [wt%] or less of the insulating film. The SiO contained in the insulating film ２ Al ２ O ３ The solar cell according to claim 14, wherein the total amount of one or more selected from the group consisting of SiN, SiON, and MgO is 50 [wt%] or more and 100 [wt%] or less of the insulating film.

17. The solar cell according to claim 14, wherein the p-type light-absorbing layer is mainly composed of a cuprous oxide compound.

18. A multi-junction solar cell using the solar cell described in claim 14.

19. A solar cell module using the solar cell described in claim 14.

20. A solar power generation system that generates electricity using the solar cell module described in claim 19.

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